The present invention relates to a wiring terminal device, which is connected to a terminal of an electric apparatus such as an electromagnetic contactor and a thermal relay attached to the electromagnetic contactor.
FIGS. 5(a) and 5(b) illustrate the above-mentioned electromagnetic contactor and thermal relay to which the present invention is applied. In these figures, a body case 3 for the electromagnetic contactor 1 and the thermal relay 2 is a resin-molded case. The body case 3 has wiring terminals 4 of a main circuit and a control circuit. The wiring terminals 4 are extended from the body of the apparatus to terminal portions 3a of a main and control circuit. Each terminal portion 3s is formed between interphase barriers.
A screw terminal corresponding to an electric wire (insulated coated wire) 6 having a compression terminal 5 is a standard equipment on the wiring terminal 4. If a strand 6a of the electric wire 6 is directly wired without using a compression terminal, a terminal device 7 is used as shown in FIGS. 6(a) and 6(b).
The terminal device 7 is connected to a terminal board 8 of the main circuit, which is extended to the terminal portion 3a, and is used to screw the strand 6a of the electric wire 6, inserted from the outside, between the terminal board 8 and a washer 11.
The terminal device 7 is comprised of a hollow member 9, a terminal screw 10 engaged on top of the member 9, and the washer 11 joined to the end of the terminal screw 10. As shown in the figures, to screw the strand 6a of the electric wire 6 inserted into the terminal portion 3a from the front, the strand 6a is pressed and screwed between the terminal board 8 and the washer 11 by screwing down the terminal screw 10. It should be noted that reference numeral 12 denotes a terminal cover that covers the terminal portion 3a to prevent electrification, an opening for inserting the electric wire 6 is formed in the front surface of the terminal cover 12, and an opening for operating the terminal screw 10 is formed in the upper surface of the terminal cover 12.
On the other hand, if the electric wire 6 is wired by using the terminal device 7, the clamp torque by screwing action is applied to the box 9 and the groove of the box 9 threading the terminal screw 10. Therefore, the member 9 needs to ensure such contour strength and thickness as to prevent deformation, and accordingly, the member 9 as a casting is used for the conventional terminal device 7.
The above-mentioned conventional terminal device 7, however, requires high cost due to a large scale casting equipment, and the conventional terminal device 7 cannot achieve enough accuracy.
It is therefore an object of the present invention to provide a new terminal device whose hollow member can easily be manufactured by using a series of press devices in a machining process by using a flat metal plate in order to reduce the cost and improve the dimensional accuracy.
To accomplish the above object, the present invention provides in the first aspect a terminal device of an electric apparatus that is connected to a terminal board of a main circuit of an electric apparatus to screw a strand of an electric wire. The terminal device comprises a hollow member connected to the terminal board, a terminal screw engaged on top of the hollow member, and an electric wire pressing washer connected with an end of the terminal screw. The hollow member is constructed by bending an elongated metal plate in a form of a cylinder such that both ends thereof are directly joined together. The elongated metal plate may have a burred terminal screw hole, press-fitted engagement projections formed at one end thereof, and engagement grooves formed at the other end thereof. The engagement projections are fitted into the engagement grooves by fitting together the engagement projections and the engagement grooves in the directions perpendicular to each other in a state in which the metal plate is bent in the form of a cylinder while the terminal screw hole is positioned on top of the member. Preferred forms of the present invention will now be described.
(1) The two press-fitted engagement projections are stamped at both sides of one end of the metal plate, and the engagement grooves corresponding to the engagement projections are notched as U-shaped grooves at both sides of the other end of the metal plate (the second aspect).
(2) The two press-fitted engagement projections are formed in parallel at the center of an end of the metal plate, and the engagement grooves corresponding to the engagement projections are stamped as window holes in a surface of the other end of the metal plate (the third aspect).
(3) According to the above-mentioned paragraphs (1) and (2), the engagement projections and the engagement grooves are joined together and press-fitted in a state in which the engagement projections are fitted into the engagement grooves (the fourth aspect).
With the above described arrangement, the sequence of machining steps from the supply to assembly of the flat strip plate as material, i.e. a machining process comprising stamping, stamping and press-fitting, can be carried out by means of a series of press devices to thus manufacture the hollow member of the terminal device. Moreover, since the engagement projections and the engagement grooves formed at both ends of the elongated metal plate are fitted together perpendicularly to one another and press-fitted, and it is possible to ensure such a joint strength as to sufficiently withstand the clamp torque of the electric wire. Further, by burring the opening of the terminal screw hole, it is possible to form the screw groove having the same width as that of the thick plate.